Solar batteries

More and more suppliers of solar products are entering the energy storage market. Technological development proceeds a rapid pace and, especially with the rising energy prices, the sale of home batteries will take off.

Until recently, a home battery system was used almost exclusively for off-grid applications to store the generated solar energy. The rise of the lithium battery has sparked a huge interest from people who want to store their excess solar energy, whether or not they are connected to an electricity grid.

With a home battery storage system, the energy can be used at times when no solar energy is available or one can even become completely off-grid and energy independent. In addition, more and more households have a home battery to further save on energy bills.

Below we discuss the advantages and disadvantages of battery storage systems and we point you in the right direction in choosing a home battery. There are several options that can be used both off-grid and on-grid.

Types of solar battery systems

The wide range of battery options and energy storage systems can be overwhelming for many people and the rapid technological developments gives rise to confusion about which type of battery is best suited for residential use. Making a choice from among the various battery types and configurations available is difficult.

Many people turn to an installer, but many companies also do not yet know the finer points of the possible configurations and we can help you with that.

3 types of battery

Roughly speaking, there are three types of battery

• Lead-acid batteries - Mostly known for use in cars. They are also used in traditional off-grid power systems.
• Lithium-ion batteries - Currently the most common type of battery and also common in consumer electronics, due to their high energy density and long life. Developments in increased efficiency are moving very quickly.
• Flow batteries - A type of electrochemical energy cell in which the energy is generated by pumping metal ions dissolved in liquids that flow through a membrane. The passage of ions from one liquid through the membrane to another liquid creates an electric current that can be collected by the electrode and used in electrical systems.

In recent years, lithium-ion batteries have supplanted lead-acid batteries because they offer a number of advantages:

• they are lighter in weight
• they have a modular construction
• they are much more efficient
• They have longer life

Is battery storage for solar energy cost efficient?

There is much debate about whether a battery system is actually cost-effective. The relatively high purchase cost and low return would mean they are not a great investment. However, due to the decreasing rates for feeding solar energy into the grid, purchasing a battery system is becoming more and more attractive.

In addition, the impending energy crisis could also make purchasing a battery system more attractive. However, for most people, the financial benefits are not decisive. Rather, they make a choice, based on principle, and want to be able to live self-sufficiently and not be dependent on the electricity grid. Using a home battery can significantly increase your independence from the power grid.

Benefits of a solar battery

• Security in the event of a power failure - With a home battery you always have power available, even during a power outage or an emergency.
• More efficient power consumption - While you normally only use 'free' power during the hours that your solar panels generate power, you store the surplus in your battery system, so that you can take advantage of it when your solar panels are not generating power.
• Reduction in costs - You save money by using less energy from the grid.
• Environmentally-friendliness - You contribute to a cleaner environment by using the generated energy more efficiently. In addition, you need less electricity from the electricity grid, which is often generated by polluting coal and gas plants.
• Energy-independence - By storing your energy, you depend on the capacity of your system, and are more independent from the electricity grid.
• Less peak-load consumption - During peak hours you relieve the energy network and contribute to a more stable public electricity network.

Disadvantages of a solar battery

• Complexity - A home battery requires a hybrid inverter or additional monitoring equipment.
• Higher Initial Cost - Purchasing a home battery comes at a cost and does not return much profit. (You purchase a battery system more for reasons of principle)
• Space - A home battery takes up more space than just an inverter. It also needs to be installed in a secure location; a well-ventilated area and out of direct sunlight.

Home battery for solar panels and electric car charging point

With solar energy alone, many average households can easily cover 50% or more of their electricity needs. This percentage can even be increased to 75% or more by using timers or 'smart' controls that turn on high-consumption devices during the day, so that they are directly powered by solar energy. These are appliances such as electric hot water systems, dishwashers, dryers, heating/cooling systems, charging points for cars.

After self-consumption has been maximized, a household can become almost completely energy independent by using a home battery. By using a battery with the right capacity, almost the entire average daily electricity requirement can be covered with solar energy, including the charging point for the electric car.

With current technologies, it is easy to integrate an electric vehicle charging station into the PV system. A charging station can easily be connected to a hybrid inverter, so it can be charged either with the solar panels or from the storage capacity of the home battery.

What capacity battery do I need?

To calculate the correct capacity, it is important to understand the basics. Battery capacity is measured in kilowatt hours (kWh) and modern (lithium) battery systems are typically modular and scalable, making it easy to find the right battery to suit your needs.

Ampere-hour (Ah) was the standard with old lead-acid batteries. This is now largely obsolete, as kWh is the industry standard for modern lithium batteries.

The key question is how much electricity the household consumes over an average period of 24 hours. Electricity is also measured in kWh. You can get a good insight into the average consumption from your energy bill. An average household consumes about 20 kWh per day, but this may vary, depending on the season.

Another important factor is how much electricity you use during the peak hours of the evening and morning. Consider your kettle, your espresso machine, a steam shower and the microwave that consume energy at the same time and so result in a peak in the power that the battery must be able to provide.

Every household is different and there is no one-size-fits-all solution, but these factors determine what capacity a home battery should have. If you are considering purchasing a home battery, consult an installer when making your choice.

Best home battery brands: buying a home battery

The largest suppliers of solar inverters such as Growatt, Fimer, Huawei, SMA and LG-Chem, also supply home storage systems. A popular option is the SMA Sunny Boy Storage inverter which can be used to connect an LG Chem battery. Below we take a closer look at a number of home batteries, so that you have an idea of the options.

FIMER REACT2-BATT

FIMER REACT2-BATT is a type of storage battery with a high voltage Li-ion battery with a long life and a storage capacity of up to 12 kWh. The modular solution can grow with the needs of any household from 4 kWh to 12 kWh and significantly reduce electricity costs Characteristics:

- Li-ion battery unit for energy storage (from min. 4 kWh to 12 kWh)

- Industry leading in energy efficiency

- Suitable for new and existing solar set-ups

- Batteries can be upgraded at any time during the life of the system.

- Flexible, modular design

- Simple and safe installation with plug-and-play connection

- System monitoring via a dedicated mobile app

- Modbus TCP/RTU Sunspec Compliant

Growatt ARK HV (High-Voltage) Battery System

Het Growatt ARK battery system has a modular design which allows additional batteries to be stacked on top of each other. The ARK HV home batteries are available in different capacities, ranging from 10.2 kWh to 25.6 kWh. The lithium iron phosphate battery (LFP) is cobalt-free, which makes it relatively cheaper. The battery lasts more than 6000 charge cycles.

The battery has an IP degree of protection of IP65 and is suitable for wall and floor installation. However, installation on a floor requires a separate pedestal. Depending on the model, the weight of these batteries ranges from 30 kg for the lightest model to 310 kg for the largest model.

Some advantages of this type of lithium iron phosphate batteries offers over lead acid and other batteries are: a longer lifespan, little to no maintenance, safety, relatively light weight, an improved discharge and higher charging efficiency.

ARK home batteries also have a LV (Low Voltage) series available.

Huawei LUNA2000 home battery

The Huawei LUNA2000 solar home battery has a scalable, modular design. A system consists of a power module and one or more battery modules. A battery module has a capacity of 5 kWh and a discharge capacity of 2.5 kWh. The heavier systems with a capacity of 10 kWh and 15 kWh each have a discharge capacity of 5 kWh.

The LUNA2000 battery module is suitable for use with both single- and three-phase Huawei inverters. Two batteries can be integrated in parallel in one solar panel installation. This allows a maximum storage capacity of 30 kWh per inverter. LUNA2000 batteries are safe and reliable thanks to the lithium iron phosphate (LFP) battery cells. Defective battery modules are automatically isolated so that the system can continue to function.

LG-Chem RESU

LG Chem's new RESU batteries are equipped with the innovative Li-ion battery cells 'JH3'. This cell technology provides powerful performance and a compact design. This makes the battery easy to mount and suitable for simple wall or floor installation for both indoor and outdoor applications (IP55). The 48V RESU models are available for SMA inverters.

SMA Sunny Boy Storage

The SUNNY BOY STORAGE multistring battery inverter allows for the connection of up to three different high-voltage batteries to one battery inverter for the first time. To connect larger batteries, the three DC inputs can also be connected in parallel.

The integrated web server enables quick and easy commissioning, also via smartphone or laptop. Due to the direct connection to Sunny Portal and Sunny Places, the energy flows in the household are completely transparent.

How much does a home battery for solar panels cost?

The cost of a home battery depends on the capacity of the battery, measured in kilowatt hours (kWh), the characteristics and the brand of the inverter used. Typical batteries for solar energy storage are available from around 700 euros to well over 10,000 euros for off-grid batteries with a large storage capacity.

When purchasing a battery system, also consider that the installation location plays a role in combination with the type of inverter used. That is why you should always consult an installer to help you make the right choice.

Is a solar battery worth the investment?

The payback period or return on investment (ROI) for most battery systems is approximately 7-10 years. With this in mind, it is significantly more cost effective to use the generated solar energy more efficiently when it can be used immediately during the day. However, for most people, the independence and continuous availability of the power supply outweighs the cost.